Standard Deviation

What Is Standard Deviation?

Standard deviation is a measure of how spread out your data is from the average (mean). In simpler terms:

• If all your trials are close together, your standard deviation is small → your results are precise.

• If your trials vary a lot, your standard deviation is large → your results are inconsistent.

Why It Matters in Chemistry

In chemistry, precision is just as important as accuracy. You might hit close to the target volume, but if your trials aren’t consistent, your results can’t be trusted.

Each time you try to dispense 15.00 mL, you record what you actually delivered using different types of glassware. Even with good technique, you’ll see small differences between trials.

The standard deviation helps you:

• Determine which piece of glassware is most consistent,

• Evaluate how much your technique (or the tool itself) affects the outcome.

What This Calculator Does

• You enter three trial volumes for each piece of glassware.

• The calculator gives you:

  • The standard deviation, rounded to two significant digits.

  • A precision rating (Excellent → Very Poor), using one universal standard for all tools.

This lets you directly compare the tools and see which one is most reliable!